High-definition imaging is becoming more and more common. Applications of high-definition imaging vary greatly. One such application is digitization of two-dimensional art as for museums, art galleries, and private collectors. The main purpose of art digitization is to capture an accurate and detailed high-definition image of two-dimensional art, to be able to restore the art to its previous condition in case of a damage. Art is also digitized for viewing, maintenance, and/or insurance purposes.
The level of detail available from a single digital photo of a work of art is limited by a number of pixels in the camera sensor. A typical digital camera sensor has a two-dimensional array of approximately 2000×3000 pixels, or 6 megapixels. A very sophisticated camera could have as many as approximately 10,000×6,000 pixels, or 60 megapixels. Even a 60-megapixel camera photographing a 2 meters×1 meter piece of art would yield only 10,000/2,000 cm=5 sampling points per cm of the art, which is not nearly sufficient to satisfy exacting requirements of a museum's conservation department. To digitize the art at a sufficient resolution higher than that of a digital camera, sophisticated flatbed scanners, operating similar to regular document or photo scanners, have been developed. Unfortunately, use of flatbed scanners is intrinsically associated with a possibility of damaging the art when removing the art from its frame, handling the art, placing the art on the flatbed, and so on. Furthermore, flatbed scanners are limited to art of a maximum size. Not infrequently, flatbed scanned images suffer from spurious reflections of light causing white spots on the images. The spots need to be manually removed using specialized software.
To increase the pixel count of an entire captured image, one can photograph the art in portions. The resulting image portions are then combined together, or “stitched”, using a variety of “stitching algorithms” available. To photograph the art in portions, one or more high-definition digital cameras are mounted on a fixed assembly. The art needs to be placed in front of the camera and somehow moved across the field of view of the camera(s) to obtain the matrix of images of portions of the art.
In U.S. Pat. No. 7,961,983, Uyttendaele et al. disclose a photography apparatus including a gimbal-mounted digital camera. Referring to FIG. 1, a prior-art mounted camera apparatus 10 of Uyttendaele et al. includes a digital camera 11 mounted on a gimbal mount 12 including X- and Y-tilt gimbal structures 13 and 14, respectively, supported by a tripod 15. In operation, the camera 11 is tilted within the gimbal mount 12 in a raster fashion to capture different portions of an art being photographed. The resulting images are then “stitched” into a single gigapixel image.
Referring now to FIG. 2, a typical set-up for the raster-scan photography is shown. The mounted camera apparatus 10 is placed in front of an art 20 in a dedicated photography room 21. Floodlights 22 are used to illuminate the entire art 20 as evenly as possible. The mounted camera 10 is connected to a computer system 23 via a cable 24. To reduce the influence of ambient light, lighting 25 of the photography room 21 needs to be turned off.
The above described known art imaging techniques share some common drawbacks. The art 20 needs to be moved to the dedicated photography room 21, or an area of the art gallery where the art 20 is displayed needs to be closed to general public. The complete art 20 needs to be uniformly illuminated, which is difficult to do. Furthermore, constant bright light from the floodlights 22 can damage the art 20. To lessen geometrical distortions, the camera 10 needs to be placed far from the art 20, which, when the room is not big enough, can limit the maximum size of the art 20 that can be imaged. Focusing is difficult due to varying distance from the camera 10 to the surface of the art 20. The image stitching process is extremely difficult due to the geometrical distortions of images of the art 20, which are dependent on angles of tilt of the digital camera 11 in the gimbal mount 12.
Until now, the task of creating professional, high-quality digital images of art has required moving the art to a studio suited to photographing large images, or closing of the gallery where the art is installed. It has also required the use of highly-skilled photographers, and/or state-of-the-art flatbed scanning systems. As a consequence, art digitization required a great deal of time and resources, and in many instances there was a considerable risk of damaging the art in the process.
It is a goal of the present invention to provide an imaging robot for automatic capturing digital images of two-dimensional art of virtually any size, without need to move the art; without need to remove the art from its frame; without need to adjust ambient lighting conditions; and even without need to close the exposition areas where the art is displayed. The imaging robot of this invention meets the above goals. Furthermore, it does not require an experienced operator or photographer because the image capturing, processing, and removal of reflections is automated. The art portions being imaged are briefly and selectively illuminated, whereby the risk of damaging the art by the lighting is considerably reduced.